Re: can not download IMAP messages with isync/mbsync

[RVP <rvp%SDF.ORG@localhost>]

On Mon, 14 Nov 2022, Mouse wrote:

> My guess is that the buffer you're testing with is near the top of the
> address space, within ~1GB of address 0xffffffff, and what you're
> seeing is due to wraparound.

Thanks for that analysis--address-wrapping was my first guess too, but,
I didn't have the time to confirm it: the 1GB was with a standalone
program; in mbsync itself, the range was much smaller--less than 1MB even.

> Also,
>
> -			uint maxlen = UINT_MAX;
> +			uint maxlen = sizeof(buf);
>
> if maxlen is passed unchanged to strnlen, I can't see how the original
> code isn't a bug; there's no point in using strnlen if you're pass a
> maxlen greater than the space remaining in the buffer your pointer
> points into.

It _is_ passed as-is to strnlen(). I chose sizeof(buf) instead of UINT_MAX
because `buf' seemed sized for the RFC-5322 recommended line-length limit
of 998 octets.

> The 9.1 manpage for strnlen says
>
>     The strnlen() function returns either the same result as strlen() or
>     maxlen, whichever is smaller.
>
> which makes this a violation of its spec.

Right, then Marko can file a PR so that this can be fixed a) either in the
ARM assembly, or b) by NetBSD-ARM just using the C version like the other
ports.

Thx,
-RVP